Book Image

OpenGL Development Cookbook

By : Muhammad Mobeen Movania
Book Image

OpenGL Development Cookbook

By: Muhammad Mobeen Movania

Overview of this book

OpenGL is the leading cross-language, multi-platform API used by masses of modern games and applications in a vast array of different sectors. Developing graphics with OpenGL lets you harness the increasing power of GPUs and really take your visuals to the next level. OpenGL Development Cookbook is your guide to graphical programming techniques to implement 3D mesh formats and skeletal animation to learn and understand OpenGL. OpenGL Development Cookbook introduces you to the modern OpenGL. Beginning with vertex-based deformations, common mesh formats, and skeletal animation with GPU skinning, and going on to demonstrate different shader stages in the graphics pipeline. OpenGL Development Cookbook focuses on providing you with practical examples on complex topics, such as variance shadow mapping, GPU-based paths, and ray tracing. By the end you will be familiar with the latest advanced GPU-based volume rendering techniques.
Table of Contents (15 chapters)
OpenGL Development Cookbook
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Implementing pseudo-isosurface rendering in single-pass GPU ray casting


We will now implement pseudo-isosurface rendering in single-pass GPU ray casting. While much of the setup is the same as for the single-pass GPU ray casting, the difference will be in the compositing step in the ray casting fragment shader. In this shader, we will try to find the given isosurface. If it is actually found, we estimate the normal at the sampling point to carry out the lighting calculation for the isosurface.

In the pseudocode, the pseudo-isosurface rendering in single-pass ray casting can be elaborated as follows:

Get camera ray direction and ray position 
Get the ray step amount
For each sample along the ray direction
    Get sample value at current ray position as sample1
    Get another sample value at (ray position+step) as sample2
    If (sample1-isoValue) < 0 and (sample2-isoValue)>0 
       Refine the intersection position using Bisection method
       Get the gradient at the refined position...